11.3.6 Attributes

A project (and its packages) may have attributes that define the project's properties. Some attributes have values that are strings; others have values that are string lists.

There are two categories of attributes: simple attributes and associative arrays (see Associative Array Attributes).

Legal project attribute names, and attribute names for each legal package are listed below. Attributes names are case-insensitive.

The following attributes are defined on projects (all are simple attributes):

Attribute Name	Value
Source_Files	string list
Source_Dirs	string list
Source_List_File	string
Object_Dir	string
Exec_Dir	string
Excluded_Source_Dirs	string list
Excluded_Source_Files	string list
Languages	string list
Main	string list
Library_Dir	string
Library_Name	string
Library_Kind	string
Library_Version	string
Library_Interface	string
Library_Auto_Init	string
Library_Options	string list
Library_Src_Dir	string
Library_ALI_Dir	string
Library_GCC	string
Library_Symbol_File	string
Library_Symbol_Policy	string
Library_Reference_Symbol_File	string
Externally_Built	string

The following attributes are defined for package Naming (see Naming Schemes):

Attribute Name	Category	Index	Value
Spec_Suffix	associative array	language name	string
Body_Suffix	associative array	language name	string
Separate_Suffix	simple attribute	n/a	string
Casing	simple attribute	n/a	string
Dot_Replacement	simple attribute	n/a	string
Spec	associative array	Ada unit name	string
Body	associative array	Ada unit name	string
Specification_Exceptions	associative array	language name	string list
Implementation_Exceptions	associative array	language name	string list

The following attributes are defined for packages Builder, Compiler, Binder, Linker, Cross_Reference, and Finder (see Switches and Project Files).

Attribute Name	Category	Index	Value
Default_Switches	associative array	language name	string list
Switches	associative array	file name	string list

In addition, package Compiler has a single string attribute Local_Configuration_Pragmas and package Builder has a single string attribute Global_Configuration_Pragmas.

Each simple attribute has a default value: the empty string (for string-valued attributes) and the empty list (for string list-valued attributes).

An attribute declaration defines a new value for an attribute.

Examples of simple attribute declarations:

        for Object_Dir use "objects";
        for Source_Dirs use ("units", "test/drivers");

The syntax of a simple attribute declaration is similar to that of an attribute definition clause in Ada.

Attributes references may be appear in expressions. The general form for such a reference is <entity>'<attribute>: Associative array attributes are functions. Associative array attribute references must have an argument that is a string literal.

Examples are:

       project'Object_Dir
       Naming'Dot_Replacement
       Imported_Project'Source_Dirs
       Imported_Project.Naming'Casing
       Builder'Default_Switches("Ada")

The prefix of an attribute may be:

• project for an attribute of the current project
• The name of an existing package of the current project
• The name of an imported project
• The name of a parent project that is extended by the current project
• An expanded name whose prefix is imported/parent project name, and whose selector is a package name

Example:

        project Prj is
          for Source_Dirs use project'Source_Dirs & "units";
          for Source_Dirs use project'Source_Dirs & "test/drivers"
        end Prj;

In the first attribute declaration, initially the attribute Source_Dirs has the default value: an empty string list. After this declaration, Source_Dirs is a string list of one element: "units". After the second attribute declaration Source_Dirs is a string list of two elements: "units" and "test/drivers".

Note: this example is for illustration only. In practice, the project file would contain only one attribute declaration:

        for Source_Dirs use ("units", "test/drivers");